Each year, millions of tons of magnesium scrap are generated in the United States. Scrap magnesium metal can be recycled into reusable magnesium metal through a process of smelting and refining. Current disposal practice is to either landfill scrap metal or reclaim it through a melting process. The costs involved in the melting process necessitate the improvement of smelting techniques and efficiencies.
Magnesium, and its alloys, is the metal of choice in the automotive industry. Magnesium is two-thirds less dense than aluminum with equal strength characteristics. The use of magnesium in the automotive industry is expected to increase in the coming years. This increase will boost the demand for magnesium metal. It will also serve to Generate increasing amounts of magnesium scrap in the future.
Metal alloys generally contain constituents of different densities and different melting points. In the case of magnesium smelting, metal is derived from the melting and refining of magnesium scrap. Magnesium scrap is melted in crucible pot furnaces. Proper mixing of the melt, as well as skimming and pumping of the molten metal, is necessary for proper development of the metal product. These procedures have been performed by hand in the past.
Typically, during the melting of scrap magnesium by smelters and die casters, mixing takes place through either convective action or by furnace rotation. Mixing is needed to prevent magnesium, alloy, and material stratification. The prior art is devoid of mechanical mixing arms or implements for the purposes of processing the molten metal.
U.S. Pat. No. 4,178,177, issued on Dec. 11, 1979, to Roebuck et al. describes a stirring mechanism for making magnesium alloys. This patent describes a loop-shaped paddle which rotates about an axis which itself rotates orbitally about a fixed axis. This loop-shaped paddle is designed to stir fluid masses including a molten metal, such as magnesium alloys. The loop is shaped so that it passes close to substantially the whole bottom of the vessel.
It is an object of the present invention to provide an apparatus and method for mixing (puddling), skimming and pumping of molten metal.
It is another object of the present invention to provide an apparatus and method where such actions can be carried out interchangeably with a single robotic arm.
It is a further object of the present invention to provide an apparatus and method which effectively causes molten scrap to be pushed under the surface of the molten metal.
It is still a further object of the present invention to increase the yield of magnesium in the smelting process by providing more efficient mixing of the melt.
It is still a further object of the present invention to provide a method and apparatus for molten metal processing which is easy to operate, easy to use, and cost-effective.
These and other objects and advantages of the present invention will become apparent from a reading of the attached specification and appended claims.